1. Field of the Invention
The present invention relates to image forming systems and image forming apparatuses.
2. Description of the Related Art
There are known image forming systems that comprise, for example: an image forming apparatus including a plurality of attach/detach sections to and from each of which a developing unit (which serves as an example of a developer container for containing developer) can be attached and detached, and an image bearing body for bearing a latent image; and a computer that is capable of communicating with the image forming apparatus and that is provided with a driver capable of instructing execution of image formation to the image forming apparatus. The image forming apparatus of the type described above forms images by developing the latent image bore on the image bearing body with the developer contained in the developing unit(s) attached to the attach/detach section(s). In such image forming systems, when image data are transmitted from the computer in accordance with instructions given by the driver to execute image formation, the image forming apparatus moves the developing units to thereby locate one of them at a developing position opposing the image bearing body. A developer image is formed by developing the latent image formed on the image bearing body, and the image is temporarily transferred onto an intermediate transferring body. The developer image formed on the intermediate transferring body is then transferred onto a medium to form an image thereon. (See, for example, Japanese Patent Application Laid-open Publication No. 2002-333756. )
In some situations, a user may wish to use a color image forming apparatus as a monochrome image forming apparatus by attaching, for example, only a black developing unit, which contains black developer, to the image forming apparatus. In order to fulfill such a desire, it is advantageous to use an image forming apparatus in which, when a developing unit is attached to each of the plurality of attach/detach sections, the image forming apparatus can be used as a color image forming apparatus for forming color imaged by developing the latent image bore on the image bearing body with the developer contained in each of the developing units; and on the other hand, when a developing unit is attached to only one of the plurality of attach/detach sections, the image forming apparatus can be used as a single-color image forming apparatus for forming a single-color image by developing the latent image bore on the image bearing body with the developer contained in that developing unit.
(1) Usually, a user makes an image forming apparatus, of the type described above, form monochrome images when the image forming apparatus is being used as a monochrome image forming apparatus, and makes the image forming apparatus form color images when it is being used as a color image forming apparatus.
There are situations, however, in which the user gives instructions to the image forming system to form monochrome images when the image forming apparatus is being used as a color image forming apparatus, or conversely, gives instructions to the image forming system to form color images when the image forming apparatus is being used as a monochrome image forming apparatus.
For the sake of achieving simplification of processes, it is preferable that processes of the image forming system are always the same for situations in which the state of use of the image forming apparatus regarding its monochrome/color modes and the instructions relating to monochrome/color image formation do not match, as with the situations described above.
One way to achieve process simplification by adopting common processes is to make the image forming system carry out the image forming processes in both situations described above. In this case, however, if the user gives instructions to the system to form color images when the image forming apparatus is being used as a monochrome image forming apparatus, then images that do not meet the user's expectations will be formed because only the black developing unit containing black developer is attached to the image forming apparatus.
Another way to achieve process simplification by adopting common processes is to make the image forming system not carry out image forming processes at all for both situations described above. This, however, would be disadvantageous for the user if he/she gives instructions to the system to form monochrome images when the image forming apparatus is being used as a color image forming apparatus, because the structure of the image forming apparatus allows it to form monochrome images even when it is being used as a color image forming apparatus.
(2) Further, users are supplied with drivers that are capable of instructing image forming apparatuses of the type described above to execute image formation. It may be disadvantageous for the user, however, if the same driver is used as the driver for instructing the image forming apparatus to execute image formation when it is being used as a color image forming apparatus, and as the driver for instructing the image forming apparatus to execute image formation when it is being used as a single-color image forming apparatus. For example, if the driver is capable of being commonly used for instructing both color-image formation and single-color-image formation, then, in cases where the user instructs execution of color-image formation when the image forming apparatus is being used as a single-color image forming apparatus, the driver will instruct the image forming apparatus, which is being used as a single-color image forming apparatus, to form color images. As a result, contrary to the user's intentions, the user may not be able to obtain the images that he/she wishes. On the contrary, if a driver is capable of instructing execution of only single-color-image formation, then the driver could only instruct the image forming apparatus to form single-color images, even when it is being used as a color image forming apparatus.